Portable electronic devices such as smart phones, smart pads, or smart bracelets are popular nowadays and are being developed to have thinner dimensions, higher capacities, and more functions. Printed circuit boards are implemented as chip carriers in early semiconductor integrated circuit flip-chip packages. However, redistribution layers (RDL) have replaced the conventional printed circuit boards in wafer-level and panel-level fan-out packages. Wafer-level and panel-level temporary carriers are used during molding process. In this way, substrates are eliminated to further reduce package thickness.
A fan-out chip package have two different structures: active surface facing down toward the temporary carrier during molding process and active surface facing away from the temporary carrier during molding process. During the fan-out chip packaging process with active surface facing down, the active surface of the fan-out chip package is attached to the temporary carrier which is very difficult for multi-chip packaging. After molding processes, the temporary carrier is peeled off to expose the active surfaces of the chips, the redistribution layer is formed on the encapsulant and the active surfaces of the chips to directly connect to the bond pads of the chips. However, bond pads are easily damaged due to cleaning the contaminations disposed on the bond pads of the chips. Furthermore, during the fabrication processes of fan-out chip packages with active surfaces facing up, bumps are pre-formed on the wafers, singulated to form a plurality of individual bumped dice, attached the back surfaces of the chips to the temporary carrier, formed the encapsulant by molding processes, exposed the connecting surfaces of the bumps by grinding, formed the redistribution layer on the encapsulant to connect to the connecting surfaces of the bumps. However, the active surfaces of the chips may be damaged during grinding processes.